Method of drawing wire filaments for incandescent electric lamps.



UNITED STATES PATENT onrrou.

FREDERICK G. REYES, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO COOPERHEWITT nmao'rmc COMPANY, or HoBoKE w,

NEW JERSEY, A CORPORATION OF NEW JERSEY.

M'J'I'JEHOID OF DRAWING WIRE FILAMENTS FOR INCANDESCEN'I ELECTRIC LAMPS.

No Drawing.

useful Improvements in Methods of Drawing Wire Filaments forIncandescent Electric Lamps, of which the following is a specification.

The present method of obtaining metallic tungsten consists in adding totungsten trioxid (W0 a suitable binding material, and then reducing inan atmosphere of hydrogen at a high temperature. The ingot thus producedconsists of metallic tungsten cemented together by a binding materialand the next step in the process is that of subjecting the ingot to aswaging process which is also carried out at a high temperature. Theswaging is continued until the ingot is reduced to a diameter thatpermits of its being drawn while hot through suitable dies until thedesired sizes are obtained. The binding material is so selected as totoughen the resulting wire.

It is adisadvantage appertaining to this process that the dies arelubricated with graphite. It is a matter of common knowledge thattungsten has a grgat avidity for carbon, where as it would I anadvantage to prevent, it possible, any cementation. This is done in thepresent method of obtaining tungsten and the result is that the tungstenwire used in tungsten lamps is in reality not a pure metal, but amixture, chemical or otherwise, of binding material and carbid.

Experience shows that a pure metal is very much more ductile than any ofits alloys. The object of the'present invention is to provide means forobtaining pure metallic tungsten in'distinction from tungsten-tungstencarbid.

To accomplish this I dissolve tungsten trioxid in boric acidat 1200 to1400 C. and electrolyze the solution thus formed. While it is impossibleto electrolyze tungsten from an aqueous solution, it is readily possibleto secure a deposit of pure metallic tungsten from a boric acid solutionat the temperatures mentioned above. The tungsten can be depositedelectrolytically upon a fine tungsten wire and when a sufiicient amounthas Specification of Letters Patent.

Patented Feb. a, was.

Application filed February 11. 191 Serial No. 818.008.

been deposited, it may be subjected to a drawing process such as is nowused, or, preferably, it may, in the early stages of the drawing, bedrawn through dies of a special tungsten-iron-carbon alloy. Such alloysare already known in the arts and tools made of it hold their edge at ared heat. The pure tungsten having, as stated, a superior quality ofductility when obtained by my process may be drawn through these specialdies, thus avoiding the expensive diamond As a lubricating materialpowdered talcum may be substituted for the deleterious graphite.

I claim as my invention:

1. The method, which consists in depositing tungsten from anelectrolytic bath of tungsten compound in an ionizing medium upon a finetungsten wire, and subjecting the resulting wire to a hot drawingprocess.

2. The method,which consists in depositing tungsten from an electrolyticbath of tungsten compound in an ionizing medium upon a tungsten core,and subjecting the resultin material to a hot drawing process.

3. The method of producing ductile tungsten wire, which consists informing a body of'tungsten, depositing pure metallic tungsten on saidbody as a core from an electrolytic bath of tungsten compound in anionizing medium, and hot drawing the resulting material.

' 4. The method of producing ductile tungsten wire which consists informing the linear body of tungsten, depositing pure metallic tungstenelectrolytically uponsaid linear body hot drawing the resulting materialwith the use of a lubricating material of powdered talcum.

5. The method which consists in forming the linear body of tungsten,depositing pure metallic tungsten thereon electrolytically hot drawingthe resulting material through dies of tungsten iron carbon alloy withthe use of a lubricating material of powdered talcum.

Signed at New York in the county of New dies.

York and State of New York this 10th day

